2 CFD SEicher · TS/CV/DC CFD Team A Brief Introduction to CFD Sara C. Eicher CERN, CH Alice....
Transcript of 2 CFD SEicher · TS/CV/DC CFD Team A Brief Introduction to CFD Sara C. Eicher CERN, CH Alice....
TS/CV/DC CFD TeamTS/CV/DC CFD Team
A Brief Introduction to CFDA Brief Introduction to CFD
Sara C. Eicher
CERN, CH
Alice
Outline of PresentationOutline of Presentation
•• What is CFD?What is CFD?
•• CFD StructureCFD Structure
•• Planning StrategyPlanning Strategy
•• Errors and Uncertainties Errors and Uncertainties
•• CFD Solving StepsCFD Solving Steps
Sara C. Eicher
What is CFD?What is CFD?
•• Solution of fluid dynamics problems by means of a computer Solution of fluid dynamics problems by means of a computer
based simulationbased simulation
Sara C. Eicher
ATLAS
ALICE
GLOBE
What is CFD?What is CFD?
•• Solution of fluid dynamics problems by means of a computer basedSolution of fluid dynamics problems by means of a computer based simulationsimulation
•• Set of partial differential equations describing conservation laSet of partial differential equations describing conservation laws for ws for transport of mass, momentum, energytransport of mass, momentum, energy
•• Components of a Numerical Simulation:Components of a Numerical Simulation:
Sara C. Eicher
CFD
Mathematical Model
Discretisation Method
Coordinate System
Computational Mesh
Approximations
Solution Method
Convergence Criteria
CFD StructureCFD Structure
Sara C. Eicher
•• CFD code consists mainly of three modules:CFD code consists mainly of three modules:
•• But firstly plan your analysisBut firstly plan your analysis
-- PrePre--processor processor –– problem formulation and mesh constructionproblem formulation and mesh construction
-- Solver Solver –– solution of the discretised governing equations solution of the discretised governing equations
-- PostPost--processor processor –– analysis and display of resultsanalysis and display of results
Planning StrategyPlanning Strategy
Sara C. Eicher
1. State clearly the objective of the study: 1. State clearly the objective of the study: what are the required what are the required results and degree of accuracy (engineering quantities, performaresults and degree of accuracy (engineering quantities, performance, nce, overall overall behaviourbehaviour, etc), etc)
2. What conditions are known? 2. What conditions are known? ((freestreamfreestream conditions, overall conditions, overall geometry configuration, etc)geometry configuration, etc)
3. Choose suitable computational model: 3. Choose suitable computational model: decide domain decide domain representation and boundary conditions to apply; can we use 2D orepresentation and boundary conditions to apply; can we use 2D or 3D, r 3D, what grid topology is most suited, etc)what grid topology is most suited, etc)
4. Get values for appropriate physical parameters 4. Get values for appropriate physical parameters (density, (density, viscosity, etc)viscosity, etc)
5. Choose suitable physical models: 5. Choose suitable physical models: is the flow is the flow inviscidinviscid, laminar or , laminar or turbulent, steady or unsteady, incompressible or compressible; iturbulent, steady or unsteady, incompressible or compressible; is heat s heat transfer, combustion, particle transport important?transfer, combustion, particle transport important?
PrePre--ProcessorProcessor
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•• Geometry Geometry ModellingModelling
•• Mesh GenerationMesh Generation
•• Physical ModelsPhysical Models
•• Boundary ConditionsBoundary Conditions
•• Setup of Solution MethodSetup of Solution Method
ALICE
PrePre--ProcessorProcessor
Sara C. Eicher
•• Geometry Geometry ModellingModelling
•• Mesh GenerationMesh Generation
•• Physical ModelsPhysical Models
•• Boundary ConditionsBoundary Conditions
•• Setup of Solution MethodSetup of Solution Method
ALICE
PrePre--ProcessorProcessor
Sara C. Eicher
•• Geometry Geometry ModellingModelling
•• Mesh GenerationMesh Generation
•• Physical ModelsPhysical Models
•• Boundary ConditionsBoundary Conditions
•• Setup of Solution MethodSetup of Solution Method
ALICE
SolverSolver
•• Input FilesInput Files
•• CalculationCalculation
•• Running TimesRunning Times
•• Monitoring Calculation Monitoring Calculation
ProgressProgress
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PostPost--ProcessorProcessor
•• Results Manipulation and DisplayResults Manipulation and Display
•• Further AnalysisFurther Analysis
•• Report FindingsReport Findings
Sara C. Eicher
Errors and UncertaintiesErrors and Uncertainties
•• ModellingModelling ErrorsErrors
•• Discretisation or Numerical ErrorsDiscretisation or Numerical Errors
•• Iteration or Convergence ErrorsIteration or Convergence Errors
•• RoundRound--off Errorsoff Errors
•• Problem UncertaintiesProblem Uncertainties
•• User ErrorsUser Errors
•• Code ErrorsCode Errors
Sara C. Eicher
CFD Solving StepsCFD Solving Steps
Sara C. Eicher
GEOMETRY SETUP2D/3D MESH GENERATION
PHYSICAL MODELSBOUNDARY CONDITIONSMATERIAL PROPERTIES
ANALYSIS CONTROL PARAMETERS
CALCULATIONCONVERGENCE MONITORING
EXAMINE RESULTSDISPLAY DATA
FURTHER ANALYSIS
START
END
NO
YES
PREPROCESSOR
SOLVER
POSTPROCESSOR